Pros
I've been working as a QA Engineer in the Atlassian team for about a year. One thing I've enjoyed is the exposure to different types of products and use cases. The team works on Atlassian Marketplace apps related to identity management, SSO, user provisioning, security, and administration, so there is always something new to test and understand. The work is fairly hands-on, and I've had opportunities to work closely with developers and product teams rather than being limited to repetitive testing tasks. If you're interested in learning how SaaS products are built and shipped, you'll get good exposure here. BDW, my favorite, having a gym inside the office premises is a nice convenience and something many employees use regularly. Overall, it's a good place for someone who wants to learn, gain product experience, and work in a fast-moving environment.
Cons
Work priorities can change occasionally depending on releases and customer requirements, so flexibility is important. It wasn't a major issue for me, but people who prefer a very predictable workflow may need some time to adjust.